It’s 10 P.M. Do You Know What Apps Your Children Are Using?

Alexander Graham Bell didn’t expect his telephone to be widely used for prank calls. And Steve Jobs was chary of children using his iThings.

But social media apps are appendages for tweens and teens. It’s one way they earn social currency. Below, a guide to what parents will (or should) be anxiously monitoring during this busy back-to-school season.